Mercurial > hg > truffle
view src/share/vm/memory/padded.hpp @ 14064:fe8d6e12c75e
Merge.
author | Thomas Wuerthinger <thomas.wuerthinger@oracle.com> |
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date | Wed, 05 Mar 2014 10:32:19 +0100 |
parents | 9766f73e770d |
children | d7070f371770 |
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/* * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #ifndef SHARE_VM_MEMORY_PADDED_HPP #define SHARE_VM_MEMORY_PADDED_HPP #include "memory/allocation.hpp" #include "utilities/globalDefinitions.hpp" // Bytes needed to pad type to avoid cache-line sharing; alignment should be the // expected cache line size (a power of two). The first addend avoids sharing // when the start address is not a multiple of alignment; the second maintains // alignment of starting addresses that happen to be a multiple. #define PADDING_SIZE(type, alignment) \ ((alignment) + align_size_up_(sizeof(type), alignment)) // Templates to create a subclass padded to avoid cache line sharing. These are // effective only when applied to derived-most (leaf) classes. // When no args are passed to the base ctor. template <class T, size_t alignment = DEFAULT_CACHE_LINE_SIZE> class Padded : public T { private: char _pad_buf_[PADDING_SIZE(T, alignment)]; }; // When either 0 or 1 args may be passed to the base ctor. template <class T, typename Arg1T, size_t alignment = DEFAULT_CACHE_LINE_SIZE> class Padded01 : public T { public: Padded01(): T() { } Padded01(Arg1T arg1): T(arg1) { } private: char _pad_buf_[PADDING_SIZE(T, alignment)]; }; // Super class of PaddedEnd when pad_size != 0. template <class T, size_t pad_size> class PaddedEndImpl : public T { private: char _pad_buf[pad_size]; }; // Super class of PaddedEnd when pad_size == 0. template <class T> class PaddedEndImpl<T, /*pad_size*/ 0> : public T { // No padding. }; #define PADDED_END_SIZE(type, alignment) (align_size_up_(sizeof(type), alignment) - sizeof(type)) // More memory conservative implementation of Padded. The subclass adds the // minimal amount of padding needed to make the size of the objects be aligned. // This will help reducing false sharing, // if the start address is a multiple of alignment. template <class T, size_t alignment = DEFAULT_CACHE_LINE_SIZE> class PaddedEnd : public PaddedEndImpl<T, PADDED_END_SIZE(T, alignment)> { // C++ don't allow zero-length arrays. The padding is put in a // super class that is specialized for the pad_size == 0 case. }; // Helper class to create an array of PaddedEnd<T> objects. All elements will // start at a multiple of alignment and the size will be aligned to alignment. template <class T, MEMFLAGS flags, size_t alignment = DEFAULT_CACHE_LINE_SIZE> class PaddedArray { public: // Creates an aligned padded array. // The memory can't be deleted since the raw memory chunk is not returned. static PaddedEnd<T>* create_unfreeable(uint length); }; #endif // SHARE_VM_MEMORY_PADDED_HPP